NOTORIOUS Barlinnie prison was at the centre of a murder probe last night after a prisoner was found strangled in his cell.

The body of a 22-year-old sex offender was found by prison officers at the Glasgow jail at around 2am yesterday.

Detectives were called out to the scene and the dead prisoner’s cellmate taken away for questioning.

The prisoner was found in his cell in E Hall on the fourth floor of the jail.

Police confirmed they were treating the death a suspicious and a post mortem examination was being carried out.

An insider said: “All hell broke loose at the jail when they found his body in the middle of the night.

“It’s the first time there’s been a murder in prison for years.

“It’s a big deal and there will a lot of questions asked about how this could have happened.”

A Police Scotland spokeswoman said: “We received a report around 2.10am that the body of a 22 year-old-man was found within a cell in HMP Barlinnie.

“A post mortem will take place to establish the exact cause of death.

“However, at this time, it is being treated as suspicious.”

Barlinnie has housed some of Scotland's most violent offenders (Photo: Getty Images)

Police refused to release a name for the dead man.

The Scottish Prison Service confirmed there had been a death at the jail but refused to comment further.

While violence in Scottish jails happens on an almost daily basis ,murders are quite rare.

In 2006, Michael Cameron was battered to death in Kilmarnock jail.

Cameron, who was on remand facing a rape charge, was attacked by David Martin.

Martin, then 20, got 24 years for the killing.

Axe murderer William Toye, 36, was murdered in Perth Prison’s D Hall in September 1996. Toye, who hacked a man to death to stop him from testifying against his brother, was stabbed to death in a war over drugs.

Scores of prisoners have been injured in custody, many of them seriously.

Race hate killer Imran “Baldy” Shahid, 36, was battered last year in an attack in the gym in Kilmarnock Prison.